The present invention relates to a callback method for telecommunications with devices adapted accordingly, in particular a callback method via a backbone.
Callback methods in which a service provider assigns a special access number to a subscriber are known in telephony. The subscriber dials this number and hangs up. A computer of the service provider calls the subscriber back with a dial-tone to a network with low tariffs, after which the subscriber may dial the number of his communication partner as usual. Other methods make it possible for the subscriber to pre-define certain destination numbers, such that these numbers are routed automatically by the computer of the service provider to a network with low tariffs.
Described in the patent application WO 97/17815 are a method and a system for telecommunications in which calls are routed in an optimal way with respect to costs, tariff costs for services between specific points in the telecommunications network, which are indicated by competing services providers and are stored in a database, being taken into consideration.
Described in the patent application WO 97/46036 is a method for a mobile satellite communications system with a GSM network infrastructure for establishing an optimal connection with respect to costs between a mobile terminal and a fixed terminal. According to the method described in WO 97/46036, cost optimization is achieved in that, based on the call number of the fixed terminal and based on a reference table with country and regional codes, stored in the mobile terminal, a switching center is selected in which the mobile device is registered.
Described in the patent application WO 97/19548 is a callback method for telecommunications in which a user in a country with high communication tariffs transmits to a network operator in a country with low tariff costs a message with his call number and with the call number of the party to be called via a non-signalling network, for example the Internet. According to the method described in WO 97/19548, this operator calls, first of all, the party to be called via a telephone network, then upon received response from the party to be called, the operator calls the calling user back via the telephone network and connects the party to be called and the calling user for speech communication.
Described in U.S. Pat. No. 5,420,914 are a method and a system for real-time selection of an economical network operator for the long-distance connection for a telephone call. According to the method described in U.S. Pat. No. 5,420,914, at a service control point (SCP) the destination LATA (Local Area Telephone Access) is determined from a call information signal of the call of a calling user, and the most economical network operator at the moment for the establishment of the long-distance connection is selected to this destination LATA is determined based on stored tariff information. According to the method described in U.S. Pat. No. 5,420,914, the long-distance connection is established using the services of the selected most economical network operator, and afterwards the connection completed of the destination LATA to the terminal with the called number.
A callback method is known from Digital Long Distance (DLD) Corporation (DLD Mobile Callback, according to www.digitcom.com of Dec. 22, 1997, filed as a US patent application) in which a local network computer (Point-of-Presence, POP) captures the called number and sends digitized call data via the low cost Internet to respective nodes (POP) participating in the method. In this callback method, the POP closest to the destination determines the most cost-effective telephone connection available to complete the call, and establishes the corresponding telephone connection between the destination POP and the local line to the local network computer (local POP). Thereafter, the destination POP completes the circuit with a second local telephone line to the destination end. Besides the low cost for establishing the connection via the Internet, the communication costs are reduced to the costs of the two local connections to the local POP and to the destination POP, the long-distance call dialed for the low tariff.
It is an object of this invention to propose a new and improved callback method for telecommunications.
According to the present invention, this object is achieved particularly through the features of the independent claims. Moreover, this object is also achieved through the system according to the independent system claim. In addition, further advantageous embodiments follow from the dependent claims and the description.
In particular, these objects are achieved according to the invention in that the callback method is implemented such that a connection with the communication terminal of the calling participant is established from a local gateway and that a connection with the communication terminal of the called participant is established from a destination gateway and that the data transmission from the local gateway to the destination gateway takes place via a backbone. Besides the low costs for establishing the connections from the gateways to the backbone, the communication costs are reduced to the costs of the two local connections to the local gateway and to the destination gateway, as well as to the costs of the data transmission via the backbone, which can turn out to be negligibly low, depending on the embodiment.
Preferably, the destination gateway and the local gateway are determined such that the current tariff from the destination gateway to the communication terminal of the called participant or from the local gateway to the communication terminal of the calling participant, respectively, are the lowest possible. Obviously, the communication costs of the two local connections can thereby be kept optimally low.
Preferably, the tariff costs from the local gateway to the communication terminal of the calling participant and from the destination gateway to the communication terminal of the called participant are subsequently compared with the tariff costs of a direct connection between the communication terminals. If its tariff costs are more favorable, a direct connection between the communication terminals of the calling and the called participant is established instead of a connection via the backbone. This approach has the advantage that it ensures that the callback variant with communication via gateways and backbone is only used when it is actually cost beneficial.
In the present invention, the current tariffs of the gateways are being monitored for the duration of the connection. If the current tariff of a more cost-effective gateway is lower by a pre-defined amount than the current tariff of the gateway used at the moment, the respective communication terminal is connected to the backbone via the more cost-effective gateway as a result of a connection change. This has the additional advantage that the communication costs can be optimized even for the duration of the connection.
Preferably, the callback method of the present invention is initiated through a special message which is prepared by a SIM-card and transmitted to a service center. This has the additional advantage that a participant (or a group of participants) may make use, by means of his (their) personal SIM-card, of personal callback services which are transferable to other communication terminals.